1. Field of the Invention
The present invention relates to stabilization systems for vehicles such as sailing vessels, ice vehicles or racing cars and a method to use the same and more particularly to stabilization systems against heeling or rolling forces imposed on such vehicles.
2. Description of the Prior Art
In the use of vehicles that are subjected to lateral forces there occur undesirable side effects on the performance of these vehicles resulting from these lateral forces. Among the factors impeding the performance of sailing craft are the leeward heel with its well-known loss of sail power and the loss of control due to weather helm or the lateral force generated by the mast and sail assembly and the leeward drift of the hull during reach or tacking maneuvers. A further aspect of the conventional displacement hull sailing craft is the induced drag resulting from the windward inclination of the keel or center board when pressed to leeward in the water by the wind. Similarly another natural force, the centrifugal force created in a turn of cars and ice vehicles has the result of lifting the runners or tires in the inside of the turn and also put undue stress on the runners or tires at the outside of the turn, resulting in poor performance of surface vehicles.
Some of the prior art has attempted to hold the hull of ships on an even keel while allowing the keel and mast to pivot under the wind force. As only one such example might be cited the sailing craft of Adamski in U.S. Pat. No. 3,972,300.
A number of prior art devices use a variety of pairs of symmetrical keels moved by various mechanical means to control the heeling of their hulls. The U.S. Pat. No. 4,044,703 to Kurtz is here mentioned as a representative example.
The difficulty of maintaining a displacement hull upright in the beached condition without bracing to the ground is solved by the movable, V-shaped symmetrical keel described in the U.S. Pat. No. 4,352,335 to Sugden. This apparatus, like the previously cited examples can reduce to a limited degree the heeling of the hull under wind force.
A number of designs have as purpose to reduce the leeward travel of the hull under wind pressure by giving the keel or center board a changed hydrofoil shape and/or a changed angle of attack in the water. As only one example of such endeavors can be named the U.S. Pat. No. 4,377,124 to Guigan.
A way to present a surface that resists leeward movement of a hull is shown in the pivoting keel disclosed by York in U.S. Pat. No. 713,830.
Among the weight shifting devices to dampen the oscillations of water craft is here cited as example the U.S. Pat. No. 3,934,535 to Culver.
In the U.S. Pat. No. 3,670,834 to Rogers is shown a hillside tractor with power operated weight transfer assembly.
The above mentioned aspects of the prior art singly or combined cannot achieve the condition of a displacement sailing craft or the roll resistant surface vehicles as embodied in the present invention.
For a sail to derive maximum drive from the wind striking it substantially sideways as in a reach, airflow should be maintained over it that eliminates spill of the wind from the tip of the sail and spanwise flow away from the hull. This is done in the present invention by giving the mast windward heel. This condition can only be achieved by efficient use of the weight shifting aspect of the keel assembly while maintaining first rate antilee drift or antiskid capacity.
The Adamski device does not allow the heel of the mast to be reduced without also reducing the antilee drift or antiskid capacity of the keel. The divided but symmetrical keels of Kurtz and Sudgen share the disadvantage that the half keel that is poised to give best leeward antidrift control is not contributing to, but is, by its leeward position even cancelling some of the antiheeling forces generated by the windward half-keel. This arrangement means that the keel assembly is inefficient in that it carries excess weight and unduly increases the required wetted area of the sailing craft.
Most importantly, tests have shown that the viscosity of water greatly impedes the swing of keels of this design. The ballasted member of the present invention was found to be at least seven times more efficient in lateral travel and heights gained than the dual-purpose keels of the Adamski, Kurtz or Sudgen devices.
The disadvantage of any device of the type exemplified by the Guigan center board is the fact that the benefit derived from lessened leeway of the hull is cancelled out by the increased heel created by an asymmetrical profile or a positive windward angle of attack of the keel in the water.
The loads on the mast and keel assemblies of sailing craft under way are massive and normally quite beyond the power of the crew to overcome quickly. Many of the cited devices require the crew to manipulate keels and masts by mechanical means such as winches and hydraulics. Particularly in competition or emergency situations this has proven to be infeasible.
By contrast the present invention provides a stabilization system for sailing craft that bas the capacity to sail in a reach with the mast heeling to windward, the crew using the force of gravity, inertia, centrifugal force or wave energy to position the ballasted member and the force of the wind on the sail to lift the ballasted keel or member into its raised position.
The disclosed method is made possible by having a separate ballasted member or keel with a minimal lateral surface swingably suspended below the hull. The crew is providing power only for locking the weighted member in selected positions to windward and elevated from the perpendicular on the hull. A separate antiskid member or center board is provided to counter leeward drift. Synergistic benefits from the windward heel are: dynamic pressure from the asymmetric shape of the submerged portion of the hull, eliminated induced drag in the water and elimination of the effect of weather helm. The greater stability offered by the positionable keel allows reduction of the beam of the hull, giving it diminished form drag. Alternately the advantages of the present invention can allow a designer to reduce the sail area, or the mass of the ballast without reducing speed.
On ice craft and racing cars the centrifugal force generated in turns on unbanked surfaces or the wind force in the case of wind sailers has the tendency not only to roll or tip such vehicles but also to reduce the adhesion of some of the tires or runners on the respective surfaces. The effect is additionally to unduly increase the pressure on other tires or runners causing them to be loaded beyond their capacity to transfer loads to the medium over which the vehicle is travelling. The disclosed weight shifting stabilizing system actuated by natural forces allows such vehicles to equalize the loads of different tires or runners, giving previously lightly loaded tires or runners more road or ice adhesion and reducing the loading of other tires or runners that previously skidded or deformed because of overloading. Synergistically the weight shifting stabilizing system effectively shifts the center of all forces on the vehicle subject to lateral external forces in the direction of these forces, reducing the tendency of these vehicles to roll, tip or heel.
3. Summary of the Invention
It is accordingly the object of the present invention to provide vehicles that have superior performance when subjected to a lateral force that has a tendency to tip, roll or heel them in the direction of such force.
Another object of the present invention is to provide a sailing craft and a method for using the same that allows sailing with a mast heeling to windward and a keel or center board inclined to leeward.
Another object of the invention is to provide a sailing craft that derives maximum speed from a given wind energy by having less induced drag in the air and in the water.
Another objective of the present invention is to provide a sailing craft that generates dynamic windward pressure on its submerged portion without increasing the leeward heeling forces acting on the craft.
Another objective of the invention is to change the effect of weather helm which has the tendency to diminish the windward performance of a boat to lee helm which has the effect of increasing the windward performance of a boat.
Another objective of the invention is to provide a weight shifting keel with a minimal lateral surface that allows the crew to swing it solely by gravity and inertia or centrifugal forces past the perpendicular and lock it there in selected positions to give maximum windward heel.
Another object of the invention is to provide a sailing craft that has good windward performance by reducing the amount of sail, beam or ballast required and reducing the wetted area to a minimum.
Another object of the invention is to provide a vehicle with an improved cornering ability.
Another object of the present invention is to overcome the disadvantages of the prior art sailing craft and surface vehicles.
The objects of the present invention are accomplished by the following embodiments, methods and steps.
In one aspect of the present invention there is provided a stabilizing system for a sailing craft having one streamlined ballasted member with a small lateral surface movable but lockable suspended beneath the hull to resist heeling forces and a second streamlined member or center board with a large lateral surface and little mass disposed beneath the hull to counteract lateral or leeward forces.
In a further aspect of the present invention the ballasted pivotable member is linked to a pivotable center board with a large lateral surface by a linkage that allows energy from the ballasted member to be transferred to the center board to pivot it to leeward when the ballasted member is pivoted to windward.
In another aspect of the invention both pivotable members have streamlined bodies at their tips that compliment each others shape when aligned together but generate windward dynamic pressure on convex surfaces that are exposed in the water to windward when the ballasted member is swung to windward and the light member is swung to leeward.
In a further aspect of the invention there is provided a stabilizing system with a ballasted member that swings about a vertical axis of rotation to provide weight shift to windward on a sailing craft.
In another aspect of the invention there is provided an energy storing power assistance means to assist the movement of the ballasted member and/or the functioning of the mechanism to selectively lock the ballasted member in various positions with respect to the hull.
In a further aspect of the invention there is provided a surface vehicle with a stabilizing system that provides weight shifting stabilization against rolling or tipping forces by using natural forces to laterally move the propulsion unit and/or the crew seating, thereby also contributing to equalize the loads on the tires or runners of the vehicle.
In a further aspect of the invention a method is provided to use the stabilizing system with a movable ballasted member on a vehicle, the method using a lateral natural force such as wind energy or centrifugal forces to shift the ballasted member, then locking it in a selected position with the body of the vehicle and completing a turn so as to change the exposure of the vehicle to the external lateral force so that the ballasted member now is positioned toward the direction of the lateral force with respect to the vehicle.
In a further aspect of the invention there is provided a method to use the stabilizing systems defined above, that method comprising the steps of: releasing the locking means prior to completing a turn of the sailing craft and causing the ballasted member to swing past the perpendicular and causing simultaneously the mast to heel leeward, then locking the ballasted member and the hull in a selected position, completing the turn of the sailing craft in order to change the exposure of the sailing craft to the direction of the lateral external force, which will bring the ballasted member to face the windward side so that even when exposed to the wind the mast will heel to windward, thereby causing at least four beneficial synergistic effects:
(a) causing the hull to generate dynamic pressure to windward, (b) maximizing propulsion force on the sail because of elimination of wind spill and induced drag on the sail (c) causing the keel or antiskid member to work with maximum efficiency by eliminating the tip vortex and reducing the induced drag in the water and (d) changing the deleterious effect of weather helm namely decreased windward performance, rudder braking etc., to the beneficial effects of lee helm.
In another aspect of the invention the disclosed method includes the use of centrifugal forces to move the ballasted member laterally outward in a turn prior to reversing the direction of the turn.
In another aspect of the invention the method is carried out by letting the ballasted member that has swung to a high position on the hull and is held there by the wind force fall past the perpendicular so as to have it carried by gravity and inertia to a further high position. The wind force will simultaneously heel the hull leeward and when locking the hull and the ballasted member together the combined effects of these movements will provide a higher position of the ballasted member on the windward side of the hull.
In another aspect of the invention the disclosed method is carried out by using the wave energy to move the hull into selected positions while the force of gravity holds the ballasted member substantially perpendicular.
In another aspect of the invention the disclosed method is practiced with a stabilization system that has two pivotable streamlined members: one ballasted to counteract heeling, the second lighter and larger, to counteract leeward drift and the method includes the step of using energy from the swing of the ballasted member to leeward to move the second lighter member or center board into a windward inclination by means of suitable connecting linkage.
In another aspect of the invention the method includes the step of generating windward dynamic forces on a sailing craft by the positioning of convex surfaces to windward on streamlined bodies or endplates at the tip of two opposingly swingable members of a stabilization system.
In another aspect of the invention the method is carried out by the use of a ballasted member that pivots substantially horizontally to shift weight to windward on a sailing craft sailing on a reach.
In another aspect of the invention the method includes the use of an energy storing means to assist in the initial movement and/or working of the locking mechanism of the stabilization system, the method including storing energy obtained from the kinetic energy of the swinging ballasted member.
In a further aspect of the invention there is provided a method that includes the step of using the centrifugal force present during a turn of a surface vehicle to laterally move a ballast to counteract the effect of wind forces or of centrifugal forces in a further turn in the opposite direction.
Further aspects and advantages of the invention will be evident in the following description.